SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '403d126cd90c6756e5de32b32445aa5ec5454bf027e951d52b021bdfcffd740a' 
  AND token = 'a2YKBenOOnH+d59E4cfCJihVhVWXwVypVquGjByQysY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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