SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '98608719313c47d1f459c88da6f1d07a6fd7f66b0b4c1142eb7ff8bf03d0afb8' 
  AND token = 'SGVGs4Bab0LWm7CiZ5ouLjWC7Xs+zc+qgF2RQp7Z7tI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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