SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51647240192bf32b85b0971eb02b588e0aead5ac9fe4d0c4e18454b38b7054cd' 
  AND token = 'm2s60s4G1RvMFsKAnvaXEvX0qLQWjwngW3N8d+1QdkU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

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