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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a42cc3df7b17da74d9a188b705d31b7c5521df011f0faaec1b195bbd10b1e551' 
  AND token = 'OLXSZNW7dmp5QtKU3qxDDqYkuQ0QHk+wWcKWttH0vqk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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