SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4912f10d31730a9f778d76532a20ac0115b7212682ee49ee40620836e370e224' 
  AND token = 'GwCThoTwdNC9toS1kkH9zMIInWx81jkYWce7ttZKZTQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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