SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c99eaf6743d8ad3dd8a737394550d6473c81be2e9838c0a509193b3c55f27b8b' 
  AND token = 'tFVQRnlTLBEkXkl05pX0ePy0tU0wmyIAckuj+S8zD/g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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