SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '17bece6d888514b3d9c9a98e0a5d6e94662e76ac8cccdab517ea1b659c147fcb' 
  AND token = '+gSTL3PLebcvxz3pm1g87/J2pZ5cXF2nrwuwVqTh5xc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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