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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8e18bb6e1bde9abeaf956c98aeffe4eef2d0e249586cbbbeb83687d7b6f0939' 
  AND token = 'Y6R9HRykTAnQCMQ1aeUpj5TjGh7rKvHIUJs4V069wQQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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