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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '627b6f2a2b9ccb67c61969e8bd9ef08ef5628b371fa8aa34bd0229ce14c7d1c5' 
  AND token = 'al98mF7KCKqMIuOw2YUgq+MMS+PLfE1OiuAuAEF9t40=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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