SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a14969a482caa39104c70ca9292dfb51a539f46d3d0f25efa5ac0383c53bdc2' 
  AND token = 'fzEIXM0kow8kaJ0hCPZzr0s22mEAdPAoWRHZJsTpiQQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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