SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b28a0da2261e0759d477a0919255509a79ff7246603e0028fe8eecaad82072d' 
  AND token = 'fwaO/Qh9izh8rkPGaxNa4MAsygk8YPgXdYMI8xHN/fM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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