SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8a3867c471eebfdd2319e9c9cc66acda5074874e74656b8403c6aca17839943' 
  AND token = 'P74jGKG7Rwq2QXYBErgXIAPVvcKpHBDFWSau5SYXmd8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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