SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7bc73e4a5905f3e646ae1610bf9b55355ac61bd98b8a79b541787da884213215' 
  AND token = 'UnOvla3zJB3LWp2uUzJfuy0m9nj+X8lzaECpyysVyY0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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