SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91732375a1b83a19b62084968ca687352ac72e42a313d4aa93a64b6adf873a8e' 
  AND token = '39ldEfk3BWycTbZ8oS0A3ki5VBMAiopdJC/4cKQ4NdA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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