SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '56c931bdfe0d7f8d42a7fce48e864c6605b077bd2a0885d48247ed5327bbaf36' 
  AND token = 'SLp2AzROzvOjiYwh9aAte8hLNw48Sp6S/7TlNDAK7X8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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