SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '16b94d9927a47aff51afd10578f0f3c14ea5c27fc17d6e59585eb90fee55f05b' 
  AND token = 'Nm0xymt0AkbBw2VHECfy+tsrOhBf4FEoetFMfSGV35Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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