SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '875da10119c1ff95bdc011d25295829ac56d017bc8ccdf563ec4ff1c6f4a3cf7' 
  AND token = 'iEXJA2Wv317aYUyljZyOkbNE4xj9E3f0oVcrKznkLaQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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