SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '96f257be714697f18a5fd84cfd333e1fbc383c101117635561524feef09daf39' 
  AND token = 'fCsuTX9POTymB6ak+8AFMOAG5YJjp8Ws7SO5pK8b2vQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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