SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c39340fba46f6be8391649e87cb349369ad47f638b9caf6851b8ce060896400b' 
  AND token = 'Fv+NeOIdzVc6KZWWME8KjT3RrIDibrFz8WI5Eldw/bE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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