SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e8d025edff8f6b0cdfa51253f840e2af511d40cdd1bfe2ead010c77ca45ef27e' 
  AND token = 'VtaovshEennSyUDxTGh4tk2EBuDhKTHDaq7Ny1Tf6Kc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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