SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76a3ca1810496c95b6c121e8e37efe587001b9b365124dd5d419e2cb90b0d26d' 
  AND token = 'epHgbpp6B5L4Bqk4K40FkGWjJY8+CelIa9R+VCuF9WI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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