SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '30e8f865c90032b6cdccc360bc15dde35743805be47883b68b8e0808755fb9e2' 
  AND token = 'jFLF5YWMnZdn6TTdG63zTjrcpI4liwva5SG+NSGWOLg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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