SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3e76e1dd2fd73232b491495867bc43f5341b58d2e2ed945e5b8d9b207fc9a76' 
  AND token = 'FKK2BJSW2VVA7Q2YSjVTH2mvqkxlUSZtYC1KyxyZsaM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

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