SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'de5fa57a3d21afbf489ce21f7bce6e1ceb3008c80fb0e07e558f9ee4e05952f8' 
  AND token = 'mTsMAqV2/FYV/2qc/HHk0HLW0BaD3a8e0NiyKexvZvc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}