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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8881ffa09ff8c35b5b9a3b5ced9b9fd2e9d848c52081d2eaffc0c668b838a0e5' 
  AND token = 'P5yJIKAFTldxc9aoI559fA3Dm+C8M9NE3IxFQM5NHsA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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