SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '17668323f452693f4d47ffe3d8854bf3fed435a78279716fcadf306fe1c66f47' 
  AND token = 'KKX/I+Q5zlQsHc9Cg0Noes/ZdLRmnQDFq9eVhA2TwFY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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