SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5e26dfd902cdbfad8c2ba3d37b79ecfe4a78011515b78ca9771f7854bdcad2f9' 
  AND token = 'j1Mqglth8NfxfZ7VhaWFzdtzhneOl/KWFhbyd85DFQw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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