SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a342a64d0a589ba0d8f37d8466734f958e0050a4dd9be1ada4d582765933da13' 
  AND token = '6J/1s8fXiBATc+6ksUTLFKPbVVzQw9x5IWPyZjvFoA4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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