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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6dcdb49e03c0bda5aa4f3c13473ed728a0e57ebfb52bbbbe4aab57ce692b4242' 
  AND token = 'NfoCESRGhVWOBrICUnu+JiC5y6+AeUGR+QRSdhzS+oQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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