SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ae8909e2f316049b2fef9a36d9944e29e523857a09c3958708b392c6e21bd017' 
  AND token = '/VEQjZos46vEzTWdkYARj3RaCK2qBU/sGh/FvcAT1Og=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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