SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20996a82c769eb5a0d7e42083daba9292ed174de86ccead5bb7b24eff7528105' 
  AND token = 'gkvrG+e/9Nif2sxMCxvOc37fbSVAUN/CetoJoq92pTs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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