SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '33446ac40d9a52a82edea78be71e0fa21b191b4cf9c9bf7a188b7c529f3456c4' 
  AND token = 'tbDBJF2yErOPGoJ/Gn1j7+tPlVXmoRpLUWHF6cAWKdY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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