SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b025cde5ed352a05399fe96f8078cdf9b940aac52747b26d5891628ae1437d9c' 
  AND token = 'BRT5Jp0WQKxhKUT2S5KFzXJVi+ze+vo+wCvKz1bjVSs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00008

JSON explain

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