SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c94435456e2cda7d852f565ac08a159d0049bff52c756313c4ab2fc744b761de' 
  AND token = 'GWLV1hYChh+/KxulfMP3licBwkuXimspAtNC3FRPDNs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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