SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a24da6a7cf4f09f87f8cfd13079a404b571d5026bf4e62db2961f143d0e2f790' 
  AND token = 'pH5rQIW1+ZuwZ+DduRVgoKN5BUfT9j9F5FGKk1mvLaI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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