SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'af12c88dd722311db45947a4d3676787d1342e8027cbc5a5dbbb1826a9f03447' 
  AND token = 'GxsgLqdSBB69wVPB+QC8QhSCiP8Fs7/i48GH+RZxuSY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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