SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd695791be025ee0000919d8e3aad7b755f6d7fccca772e940d547676d87581cf' 
  AND token = 'fZf6qQ70vximvb2ssS+CWAj0LXFMQ6jCoC9C7XhUBsg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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