SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '374a62a63ab43b2bf2880cbdf53626305345f527ea49eee6107f7b6234bbe407' 
  AND token = '78V77iaxSSBq373uE8GCnUmH0bzIzishccCELyWeYzA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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