SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '819027b3cf55bf1fb216fc16f4262007231631b956ce01a387c1790115af38f2' 
  AND token = 'wUhCyHLM8QyN20g2HtA087W6qX/StbL2hi5UZPauCYU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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