SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e3b35799626a3c6ad1a6010df60aa5ed89d0ddd7f515976f7bd952811204bd31' 
  AND token = '6MN2hSdkhlydMEuV4s95kb45ffxR4E7nlHaUxXSQscQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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