SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '88c1d6bab6bb6b737f1b4b82f378aacf0fd99e12d98e51dc27767674ec01091a' 
  AND token = '5vAkaoUDGazBf5JAmkaPmFkyC2o358zxlUsHwDqufS0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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