SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'c556204844862420bf89d3c98b3a520728475dae48e23dade4ff6e350c0efd0e' 
  AND token = '8KGxWpP9+wrarpnB/mGWD7LolFHxq0WdQSxRkg4IoVQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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