SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4d40ed12be938b1c19122dadb964c25091a20571385a92d797b9e7e5da1caa7c' 
  AND token = 'dHokBeCXEuNaMMKN+FBAkiyEzZvGV+we03jMAAgpZgU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}