SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fc0b78c60b63606797226f4d4c78a135cf4a955fc51eb24d40882f987bd5baae' 
  AND token = '/6dhXdiqvkPlj1TT9UDoMTPgixOML3POKNHVjz2zwlQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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