SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd08c08352a63db118239448271b70cc53a5745f5c56f1b1e603d897b4ef40bab' 
  AND token = 'tux1rspoi08W6/TQGd7fn1AAs+N423UcLK8w5BVYlGk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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