SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e755f85821697e5344bdd9733b7e67d75aa98c727b760e662d456f26175263f7' 
  AND token = 'iXF7eph/EpwIH2YotepL0gzr+LGasQCAMDLCYtR/5GI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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