SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a2708ea0439e8ff840cd4ae00cebd2edf78bf1bc2370b019b075af34f111701' 
  AND token = 'h8PhQSPo9UT5odyDoXavMiWm1J6wfqaG0IrfYtJCvYU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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