SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31064a1b95d70f0b90cdd7cb41eccb9e6333d800a32d855b22e6f959dce5f99a' 
  AND token = 'SEZABk5euuVrJRB28ScwQKt356mGvhapylrFXltBpwA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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