SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4a5fd17757c44938b3dd260f4abe1c1827884470f5e2438872eaf65741c904f4' 
  AND token = 'TS4JuCs9pBRTRhc1uSV1cvDqjEZKaK+wCkGcLxck3+0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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