SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50ebffd56616fab64a706fe8a7acbb70da538d64f36243376a4d016dfd318a52' 
  AND token = 'ByHIV89ftTMsC9JWGGdz4o4i0cQxVlQbiYzRbdNoxJ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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