SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ec5878dafdb6a7d9cfa98000ced51c7335bc79be569c4b93a20f0a47f06f28ad' 
  AND token = 'ITkd2iYSu0GT8LfFqY8zT7IEEUs+4PY/KWVMGFMMEbY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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