SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f06da51a63ac857841d311b68cc223d5da6d98643646d664e79967d5dd8dd81' 
  AND token = 'PSXKQnx5mOmShHjV0zIkkXYSVjoCe6EIizcrF8tDKLQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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