SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '08be7442a4943c5147ac77c29c6790140102faca273f12acc0b051b918a20e67' 
  AND token = 'rXlykpUQS1jiYHZrIj4wsYujURPFEnGuuj2PFSyXvwE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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