SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c9e971fdd1ffdd5550ed8b3b5d1c1791ffedfe4306bb3c13bf7e39c38ab37155' 
  AND token = 'gqmgaFrgzfceGtM5GT53jxK5yiI5eOcA6+Gm/oGAVmE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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