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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8df44d0bbfcacdc4e207559a9744cdc71aedb5b3ec34c520c13a870bdf9b224' 
  AND token = 'k2Rr4ddeQnXsa/Fpoh9h1uYo2EuwflSCiWg1uT9mR6U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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