SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '17761f3efe4a1330e98792e621dc154fbb2f6bd50e729e12cc438d684f42db74' 
  AND token = 'vy9+a8k2G7hKGlGtwcLD+dqJhs7boJZ6VC0V7fiz2EQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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