SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a551f7c256df91664550dd196931a1ad2cbbb9dc89607027a168cfe369efe7d3' 
  AND token = 'l6wob/cHO5IlySC0ahKzOinBp+fgj6GOoWKiY+wW5f4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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