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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b2e3c092f52dbd03ceb3acc5e6ad2e6a37436abc1766724cbcb4de8a98e0e572' 
  AND token = 'PPLsw4XCo1OezlMlFlUynAg/a33nx3iaxS+jRMsAVkA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}