SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5cdcd7226845ac753b9a312837e91eecbed5f063248b4b8dad9ca20b53fec93' 
  AND token = 'OKGlLgCNy+1JMp2NvT8UiMF86KXlmRQQ6oD3sh1BzK4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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