SELECT 
  1 
FROM 
  q_lock_keys 
WHERE 
  key_id = 'de755a718915043c2f9a4c513fef0f2da9f9cdff8c0b7200e1456625429eeac0' 
  AND token = '9maIHZzntWd8hBP1ZgvMuaDHFP0CZ+k2s5Gx3AsHG/8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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