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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b0beaed96309e2dcb5c13f9c7b2f00f661f3dd98433d45d882805aa9e4fcc30f' 
  AND token = '3n2r7ekxO0Siu1L5ueFZ6Gt1GHEGsUhteIZ+DcT7XSs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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