SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c56e6eec26cbbc0bfd7c9571f8f59dd2403cbdfa73abf3d8f712f971dc45b743' 
  AND token = 'yXurm/EZfcNFeqSd9BJzkNYBOd2CyFfJrv/uJ3SJjKA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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