SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ef6d1dc28aa7727472982a5786d3745509696861edc074dc620991a9067021d0' 
  AND token = 'iuwlN+REwL+iSHObtq8mJyhwyHl40mTLuW0PjXWUokM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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