SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d7cc6f0352db7823edf1f0b6d5a03628fb3547c1d4c281751aaa39dd838f64e' 
  AND token = 'zWRWZ8sh2jzSDKC+yOhV2Rwi2dJo3FdvKNPYvc7YNZE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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